See-through head-mounted displays (HMDs) provide the ability to augment what the wearer sees with virtual objects. In other words, the HMD augments the HMD wearer's view of the real world with virtual imagery to provide an augment reality view. However, those virtual images can easily become distracting and obtrusive, drawing attention away from the real-world and occluding the HMD wearer's normal (non-augmented) view. This may present a challenge particularly in applications of “always-on” wearable display devices, especially when considering mobile, outdoor, and in-activity scenarios.